There is a semiconductor processing system of the cluster tool type, which has load-lock chambers and vacuum process chambers disposed around a vacuum transfer chamber. Further, there is a vacuum processing system that has a load-lock chamber and a vacuum process chamber stacked one on the other to reduce the installation space (for example, Jpn. Pat. Appln. KOKAI Publication No. 2001-160578). Vacuum processing systems of this kind includes gate valves respectively disposed between chambers to maintain the chambers and so forth airtight, because target substrates need to be transferred within vacuum environments.
FIG. 10 is a sectional side view showing a conventional vacuum processing system. In FIG. 10, process chambers 2 and load-lock chambers 3 are connected to a transfer chamber 1. A gate valve 5 is disposed between the transfer chamber 1 and each of the process chambers 2 and load-lock chambers 3. The transfer chamber 1 is provided with a transfer robot 6 disposed therein to transfer a target substrate between a load-lock chamber 3 and a process chamber 2, or between two process chambers 2. In general, a gate valve 5 used in this field has a valve plate for opening/closing a target substrate transfer passage, wherein the valve plate is arranged to slide in a direction perpendicular to a direction in which the passage penetrates (for example, Jpn. Pat. Appln. KOKAI Publication No. 2-113178).
In the conventional vacuum processing system shown in FIG. 10, vacuum chambers, such as the process chambers 2 and load-lock chambers 3, are stacked one on the other, so that the number of process chambers 2 and load-lock chamber 3 can be increased without increase in the installation area. However, where vacuum chambers are stacked, the gate valves 5 are inevitably arrayed in the same vertical direction. As a consequence, a problem arises such that a sufficient configuration space cannot be ensured for the drive system of the gate valves 5, and thus the number of vacuum chambers to be stacked and the intervals therebetween are limited.